In this article we look at Equine health in particular, Laminitis, Equine Metabolic Syndrome, and Equine Cushing’s Disease. We discuss how to tell the difference and best manage them.

Laminitis

Laminitis (also known as founder) is a potentially crippling condition of horses and ponies which can be fatal in severe cases. Advanced laminitis causes severe chronic pain, eventually leaving sufferers unable to stand at all.

By definition, laminitis is inflammation of the ‘laminae’ of the foot – the sensitive soft tissue structures that attach the pedal bone of the foot to the inside of the hoof wall. Inflammation and damage to the sensitive laminae causes extreme pain and can lead to instability of the pedal bone in the hoof. In severe or chronic cases it can lead to irreversible rotation and/or sinking of the pedal bone within the hoof capsule. All four feet can be affected, although the fore-limbs are more frequently and severely affected than the hind-limbs as they support around 60% of the horse’s weight, while the hind-limbs support the other 40%.

What does laminitis look like?

In the initial stages, laminitis may present with signs such as:

• Reluctance to move about
• Sore-footedness, especially on hard ground
• ‘Leaning back’ stance
• Weight shifting from foot to foot
• Excessive lying down

Horses or ponies which have suffered chronic (ongoing) laminitis may have signs of abnormal hoof growth such as divergent hoof wall ‘rings’ and long, dished toes.

Prolonged and severe inflammation of the lamina can cause the hoof wall to lose its attachment to the underlying bone. As the horse bears weight down through the leg the bone can rotate away from the hoof wall, and sink closer to ground. In severe cases the bone can protrude through the sole of the foot.

It is important to note that laminitis can affect all breeds of horses, not just fat ponies.

What causes laminitis?

Laminitis is a complex condition with a range of potential causes and underlying conditions:

Nutritional causes– e.g. over-feeding, gorging on carbohydrate dense feeds
Metabolic conditions – e.g. Equine Metabolic Syndrome, Cushing’s disease
Toxins – e.g. grain poisoning, retained placenta in broodmares
Traumatic causes – e.g. over-trimming, repeated concussion on hard surfaces and lack of trimming.

Diagnosis & treatment

We will be able to make a diagnosis based on medical history and examination, and with the aid of X-rays. Treatment will vary depending on the underlying cause but is generally aimed at reducing the inflammation in the feet to prevent or limit irreversible structural changes.

Hoof x-rays confirm the position of the bone within the hoof which is useful for assessing severity and planning trimming or shoeing. Remember once the lamina has separated it can never be re-attached. Some horses and ponies can continue competing successfully with good management, but unfortunately the quality of life for some is irreversibly impacted.

Managing a laminitic or at-risk animal requires dietary management (feeding a low sugar diet and restricting overall feed intake), remedial shoeing or trimming, and anti-inflammatory medication as required.

Equine metabolic syndrome: be cruel to be kind

Equine metabolic syndrome (EMS) is a very common disease of equine animals, especially ponies. It can have dire consequences if not properly managed including chronic obesity and laminitis. Obese ponies are at severe risk of hyperlipaemia or ‘fatty blood’ which can cause death.

Ponies and small horses evolved to survive in very harsh conditions where rich feed was sparsely available. To survive they became small, needing less feed, and their endocrine (hormone) system developed an inability to adequately process sugar-rich diets. Nowadays ponies are kept domesticated, often where ample feed is available – which has led to the emergence of EMS.

Ponies, not used to such a rich diet, are prone to persistently high levels high levels of insulin in their blood. Insulin is the hormone responsible for lowering blood glucose to the normal level, and ponies can become resistant to the effects of their own insulin. Similar in some ways to type 2 diabetes in humans, insulin resistance causes fat to be laid down excessively and harms the health of the lamina in the hoof.

Signs of EMS include:

• easy weight gain
• cresty neck
• abnormal fatty deposits
• chronic laminitis

EMS is often suspected based on these symptoms, but the diagnosis can be confirmed by blood tests. The condition can be successfully managed by controlling a pony’s diet and encouraging exercise. At risk or affected ponies must be fed a diet low in simple carbohydrates including grain, concentrate feeds and often access to pasture must be restricted. This is what is termed a low GI (glycaemic index) diet. Medications can be prescribed to aid management in severe cases, and any signs of laminitis should also be addressed.

Equine Cushing’s Disease

Cushing’s disease is a common condition of older horses, affecting up to 75% of horses aged 18 and over. The technical name for the condition is Pituitary Pars Intermedia Dysfunction (PPID), as the underlying issue is over-activity of the pituitary gland (a small gland located beneath the brain). Excessive quantities of hormones such as “ACTH” are produced and this leads to increased levels of the stress hormone “cortisol” in the body.

It is these abnormal hormone levels that lead to the clinical signs typical of Cushing’s disease:

• Long wavy coat or a failure to shed properly, otherwise known as “hirsutism”
• Bouts of founder, or “laminitis”
• Muscle wastage and “pot-belly”
• Increased drinking and urinating
• Increased sweating
• Low demeanour
• Immune suppression, which can manifest as infections such as skin conditions, chest infections, foot abscesses, parasites, and dental disease

The disease progresses slowly, gradually becoming worse over time. Early signs may be difficult to spot; sometimes it may seem as if your horse is just having a few “off” days. Your vet will be able to make a diagnosis based on clinical signs and blood tests for hormone levels.

Treatment for Cushing’s disease is quite effective and involves a medication called pergolide, available as an oral liquid or tablet (that can be dissolved and mixed in feed) given daily for the rest of the horse/pony’s life. A positive response may be seen within 6-12 months with an improvement in demeanour, coat condition, body condition, and soundness.

Horses with PPID require extra attention with regard to dental care, hoof care and parasite control. With good management, there is no reason why horses with PPID cannot live a long and normal life and continue in normal work.

Diet Options for Laminitic Horses/Ponies

Eliminate pasture access until there is evidence of improvement. Sometimes this never occurs and lifelong management off pasture or by use of a grazing muzzle. Aim to reduce non-structural carbohydrate content to < 10% of dry matter

Fibre/roughage:

Feed approximately 1.5% of body weight per day =7.5kg/day for 500kg horses.

If overweight reduce to 1.25% of body weight.

• Soaked lucerne hay (or possibly mature stalky lucerne) – soak for at least 60 mins and discard water prior to feeding. Still high protein feed source but water soluble vitamins are lost in this process and must be supplemented
• Teff Hay
• Tested low sugar meadow hay
• Soaked beet pulp e.g. Speedi-beet

(avoid hays such as ryegrass, oaten, wheaten or barley = high in sugars)

The only way to truly know if the hay is safe to feed is by feed testing to determine that the carbohydrate content is less than 10-12%.

Pellets:

• Low GI pellets (low in sugars) that is safe for laminitics
• Sugar and starch levels < 12%
• Pellets are only required if the horse needs more calories and gain weight. If the horse is overweight then vitamins and minerals can be gained from a low calorie balancer concentrate.

(avoid cereal based grains – oats, wheat, rice, barley. Also bran, pollard and any form of steam flaked or extruded grain)

Supplements:

• Equishure – hindgut balancer, recommended over other founder supplements
• vitamins and minerals may be needed to address deficiencies in hay. Balancing products can be used such as “Prydes easikeeper”
• additional protein may be needed – soybean, canola meal, cracked lupins
• vegetable oils can be fed to increase bodyweight
• No molasses or sugary treats

Pasture:

• Feed hay before turning out to pasture to limit pasture feeding
• Pasture sugars are lower in the morning (except after frost) – turn out to graze in the morning for less than 1 hour and bring them in before 10am.
• Limit pasture access to less than 90min in spring and autumn.
• Strip grazing and grazing muzzles can also be used
• Avoid ryegrass, phalaris and fescue dominant pastures, as well as rapidly growing clover pastures in spring

Exercise

• Horses should not be exercised when lame.
• Can improve insulin sensitivity and metabolism
• Not suitable for all cases – dependent on the physical status of the horse, particularly the hoof structure and function.
• Start with 2-3 exercise sessions per week. Sessions should be performed at a trot or higher intensity (heart rate >120-150 bpm) for 20-30 minutes.
• Gradually increase the intensity and duration to 5 sessions per week.

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